Foam fire extinguishing system

ABSTRACT

A high expansion foam fire extinguishing system to be coupled to independent sources of water and foam concentrate. A single, common pressurized source urges the water and foam concentrate into a non-vented pressure reducing valve to proportion the mixture of water and foam concentrate for delivery to a foam generator having a plurality of nozzle members and a stratified screen to produce high expansion foam upon activation of the system by a fire detecting sensor.

United States Patent [1 1 Stults 1 Aug. 7, 1973 [54] FOAM FIRE EXTINGUISHING SYSTEM 3,142,340 7/1964 Jamison 169/15 {761 Inventor: Howard 7630 S-Bright, 3152333 (211323 1222232113... ""iiiiiiijiiii: i231 whmler 3,465,827 9/1969 Levy et al. 169/15 x [22] Filed: May 2, 1972 [21] Appl. No.: 249,724

Related US. Application Data [63] Continuation-in-part of Ser. No. 160,810, July 8, 1971, Pat. No. 3,709,302, which is a continuation-in-part of Ser. No. 782,343, Dec. 9, 1968, Pat. No. 3,592,269.

[52] US. Cl. 169/9, 169/15 [51] A62c 35/46 [58] Field of Search 169/2 R, 5, 9, 14,

[56] References Cited UNITED STATES PATENTS Dion-Biro 169/9 X Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-Michael Mar Attorney-Spensley, Horn and Lubitz [57] ABSTRACT A high expansion foam fire extinguishing system to be coupled to independent sources of water and foam concentrate. A single, common pressurized source urges the water and foam concentrate into a non-vented pressure reducing valve to proportion the mixture of water and foam concentrate for delivery to a foam generator having a plurality of nozzle members and a Stratified screen to produce high expansion foam upon activation of the system by a tire detecting sensor.

16 Claims, 9 Drawing Figures PAIENIEnwc mu sum 1 0F 3 FOAM FIRE EXTINGUISIIING SYSTEM This is a continuation-in-part application of my copending application Ser. No. l60,8l filed July 8, l97l now U.S. Pat. No. 3,709,302 which was a continuationin-part application of aco-pending application Ser. No. 782,343, filed Dec. 9, 1968 issued as U.S. Pat. No. 3,592,269 on July 13, 1971.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of foam fire extinguishing systems and particularly those foam fire extinguishing systems capable of delivering high volumes of foam and being especially adapted for installation in an enclosed structure.

2. Prior Art An efficient and highly reliable high expansion foam system for the extinguishing of a fire in a building or other structure has long been a desired goal. High expansion foam is a relatively new development for fighting fires, especially in buildings or other enclosed structures. The prior art discloses some high expansion foam fire fighting devices, both portable and fixed installations. For the purposes of thisinvention, the term high expansion foam" will be understood to define a foam which expands a given volume of water together with a concentrated mix (in solution) from 300 to 1,500 times its original volume.

One of the devices disclosed by the prior art generates high expansion foam through the use of a source of foam concentrate, but requires that air be mixed therewith through an air stream created by rotation of an external fan. The foam is formed by the flowing of air through a screen after the stream has been wet with the spray of foam concentrate. This device specifically requires the use of a fan to inject the air required to form the foam.

Thespresent invention solves the need forexternal air moving equipment and uses no injecting force to draw in ambient air other than the partial vacuum created by the flow of foam concentrate. The ambient air is drawn in by the partial vacuum without the need of any fan or other air moving equipment."

Another device disclosed by the prior art requires a tubular casing enclosing two sets of nozzles, the firstset being connected to a source'of foam concentrate, the second set of nozzles being connected to a source of carbon dioxide. A foamforming net is disposed in front of the two sets of nozzles to produce foam from the mixtrue of carbon dioxide and foam concentrate. The device requires the combined action of carbon dioxide and the foam. producing concentrate and as a result requires the inclusion of additional pressurizing equip-. ment and nozzles for the disposition of carbon dioxide. The present invention requires no additional source of mixing agent and therefore obviates the problems raised by the described device. In the present invention, the air is drawn into the foam generator solely as a result of the partial vacuum, created by the output of foamv concentrate.

Self-contained high expansion foam fire extinguishing systems are known to the prior art, an example being thatdisclosed in applicant's U.S. Letters Pat. No. 3,592,269. The improvement over that set forth in U.S.. LettersPat. No. 3,592,269 and other devices disclosed by the prior art involve the ability to increase the velocity. of foam which can. be produced by the high expansion foam generator. The characteristics which must be improved are a function of the aqueuous solutionof foam concentrate and the volume of foam produced. The system defined by applicant s U.S. Letters Pat. No. 3,592,269 can produce a velocity of approximately 300 cubic feet per minute at a supply pressure of 90 pounds per square inch. The system defined by applicants U.S. Pat. No. 3,709,302 can produce approximately the same volume of foam at a reducedpressure of approximately 35 40 pounds per square inch. This system cannot produce higher foam velocities by increasing the pressure used. The present invention provides the ability to approach the theoretical maximum foam velocity of approximately 650 feet per minute.

The present invention substantially solves the problems which have existed in the devices disclosed in the prior art. The present invention utilizes a stratified screen which substantially improves the velocity of foam produced and independent sources of water and foam concentrate which can sustain foam velocities produced. In addition, the present invention simultaneously provides for elimination of the effects of deleterious environmental conditions encountered by those systems described in the prior art.

SUMMARY OF. THE INVENTION approaching 650 feet minute at practical supply pres sures.

, The high expansion foam fire extinguishingsystem utilizes independent sources of expansion foam c0ncentrate and water. When a sensor detects the presence of a fire, a valve is opened, placing the water source and high expansion foam concentrate under pressure from a common pressure source such as inert gas, typically being gaseous nitrogen. As: an alternative to the pressure source of inert gas, a tank of water could be coupled to a pump to provide a water head, the pressure of the water head utilized to provide the motive source for the foam concentrate. Another alternative would be the utilization of pressure available in conventional water mains. Placing the high expansion foam concentrate fluid under pressure forces the foam concentrate fluid into a pressure reduction valve for mixing with the water source. The water-concentrate mixture is transferred into a manifold having a plurality of attached nozzles. When the concentrate mixture is forced through the nozzle, a cone of liquid concentrate is emitted. t

The cone of a liquid concentrate is emitted into a foam generator defined by an upper wall, a bottom wall, a pair of side walls, a rear wall and a multilayer screen. The structure of the foam generator insures that the stratified screen is substantially parallel with the floor or other surface of the enclosure within which the present invention is disposed..The top wall and bottom wall of the foam generator extend upwardly from the screen and at an acute angle therefrom. The bottom wall is terrninateda suitable distance from the screen to permit insertion of the foam concentrate input and the foam emitting nozzles. The topwall is terminated by a rear wall of the foam generator, the foam generator being enclosed by appropriate side walls. As mentioned, the foam concentrate input is inserted through an opening of the foam generator formed by the bottom wall, rear wall and side walls of the foam generator. The manifold of foam emitting nozzles is disposed within the interior of the foam generator, the nozzles being directed toward the screen. The axis of the cone of foam concentrate is substantially parallel to the angle of the top and bottom walls of the foam generator.

The foam is formed by a combination of air and high expansion foam concentrate striking the screen. Air is drawn through the orifice defined by the bottom, rear and side walls of the foam generator. A substantial portion of the air heated by the fire will only enter the foam generator at this formed orifice because of the upper wall and rear wall fully cover the nozzle output.

The screen constitutes a multi-layer structure, the layers being metallic honeycombed sheets each having the structural requirements needed to provide sufficient surface area to create the requisite agitation. The honeycombed screens each provide a suitable and different ratio of hole area to surface area to utilize the available free energy in the vicinity of the screen openings. The nozzles are spaced along the manifold at a predetermined distance that is necessary to insure full coverage of the screen surface. Since the cones formed by emitted concentrate fully cover the screen, the system constitutes a linear generator in that an even distribution of foam is created along the entire length of the foam generator. The nozzles are disposed at an angle with respect to the floor of the enclosure to provide that the axis of the cone of emitted foam concentrate is substantially parallel to the top and bottom walls of foam generator and also to provide substantially uniform distribution across the screen.

The foam emitted from the screen is directed downward because of the orientation of the screen. The heated air is drawn through the foam cooling the air. The foam will continue to be generated cooling the entire area of the building. Since the foam has a high water content, the tire will be'extinguished. The high expansion foam concentrate contains a detergent which acts to clean the inner areas of the buildings as well as extinguish the fire.

It is therefore an object of the invention to provide a high expansion foam fire extinguishing system which utilizes pressurized external water supplies.

It is a further object of the invention to provide an improved fire extinguishing system which utilizes a high expansion foam concentrate.

It is still a further object of the invention to provide a foam generator without theme of motors, fans or other air moving devices.

It is yet another object of the invention to provide a linear foam generator.

It is still yet another object of the present invention to provide a high expansion foam fire extinguishing system capable of supplying foam at velocities up to 650 feet per minute.

The novel features which are believe to be characteristic of the invention, both as to its organization and method of operation, together with further objectives and advantages thereof will be better understood from the following description considered in connection with the accompanying drawing in which a presently preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawing is for the purpose of illustation and description only, and is not intended as a definition of the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic view, in partial cross-section, of the present invention installed within a building and in a manner which is employed to extinguish a fire which may have occurred within the building.

FIG. 2 is a cross-sectional view of the proportional mixing valve of FIG. 1.

FIG. 3 is an enlarged, side elevation, cross-sectional view of the foam generator of FIG. 1 in accordance with the present invention.

FIG. 4 is an enlarged, front perspective view of the foam generator of FIG. 1.

FIG. 5 is a perspective, fragmentary view of the multilayer screen forming part of the generator of FIGS. 2 and 3.

FIG. 6 is a partial, crosssectional view of the multilayer screen taken along lines 6-6 of FIG. 5.

FIG. 7 is an enlarged sectional view of an exemplary nozzle as may best be seen in FIGS. 2 and 3 forming part of the foam generator.

FIG. 8 is a schematic view showing the discharge cone of the fluid solution as it exits from one of the nozzles forming part of the generator of the present invention system.

FIG. 9 is a graph comparing manifold pressure and foam velocity for the present invention system and one not constructed in accordance with the present invention.

DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT building 10 is numbered 14 and the interior wall 15.

The ground or the floor of the building is numbered 16. The present'invention'foam fire extinguishing system utilizes an external source of water to be mixed with a source of foam concentrate in accordance with the present invention. A source of inert gas 17 is supplied through line 18 and actuating pressure regulator valve 19 to supply a pressure source to water tank 20 and container 21 of foam concentrate through line 22. The output of water tank 20 and foam'concentrate tank 21 are supplied through lines 23 and 24 respectively, the outputs of containers 20 and 21 being proportionally mixed at proportional mixing valve 25. The aqueous solution of foam concentrate is output form proportional mixing valve 25 and connected to foam generator 11 by line 26. The manner in which the water supply from tank 20 and the foam concentrate from tank 21 are mixed at proportional mixing valve 25 will be explained in detail hereinbelow.

Foam generator 1 l is constructed of top wall 30, bottom wall 31, rear wall 32 and a pair of side walls enclosing a cavity between top wall 30, bottom wall 31 and rear wall 32. As shown in FIG. 1 and FIG. 3, top wall 30 is typically suspended from ceiling 12 by chain 13, top wall 30 and bottom wall 31 being substantially parallel. In addition, a cooperating bottom panel 33 depends from rear wall 32 substantially co-planar with bottom wall 31, bottom wall 31 and 33 defining an orifice therebetween. Side walls notshown in FIG. 1 and FIG. 3 are coupled to the side surface of top wall 30, rear wall 32 and bottom walls 31 and 33 to fully define the orifice opening into the inner cavity of foam generator ll.

The portions of top wall 30 and bottom wall 28 nearest floor are adapted to receive multilayer screen 34. Multilayer screen 34 is substantially parallel to floor 16. As can be seen in FIG. 2 and 3, multilayer screen 34 is comprised of a first honeycombed layer 35 and a second honeycombed layer 36. The details relating to honeycombed layers 35 and 36 shall be explained in detail below.

Referring again to FIG. 1, the foam system is activated when sensor 37 detects the presence of heat incident to a fire. Sensor 37 is a heat detector which initiates an alarm upon detecting an ambient temperature typically at a value of 135 F. Sensor 37 is a conventional heat detector of the type manufactured by the Walter Kidde Corporation. Although the scope of the present invention is broad enough to encompass other types of heat sensors, the preferred embodiment of the present invention utilizes that described hereinabove. The output of sensor 37 appears on electrical line 38 and energizes a relay pack 39 which produces an electrical signal on signal lines 40 to the actuating pressure regulator valve 19. Pressure regulator valve 19 is an electrically activated device regulating the pressure to be imposed upon the contents of concentrate mix tank 21 and water tank 20. The pressure regulator valve 19 can be set for outlet pressures typically in the range of 40-80 psi, the preferable operating range being above 60 psi. One of the advantages of the present invention fire extinguishing system is to permit the generation of high quantities of foam at high velocities while requiring only relatively low pressure equipment for movement of the foam concentrate. Where the structure of the present invention utilizes a set of eleven foam emitting nozzles to be explained hereinbelow, approximately 3,000 standard cubic feet per minute can be generated with a solution delivery rate of 28 gallons per minute at 80 psi. The ability to generate equivalent volumes of generated foam at lower pressures substantially reduces the cost of the equipment as well as making the system easier to fabricate. Activating pressure regulator valve 19 is typically an appropriate type manufactured by Accessory Products Corporation, Whittier, California, a division of Textron Industries, al-

though other suitable commerically available valves 7 can be used. By. opening actuating pressure regulator valve 19, the gaseous contents of container 17 is caused to flow through line 18, pressure regulator valve 19, line 22 and impose the appropriate pressure upon the contents of concentrate solution tank 21 and water tank 20. Since the foam concentrate and water tanks 21 and 20 respectively are under pressure, the foam concentrate and waterare forced into lines 24 and 23 respectively. I

Upon actuating the pressure regulator valve 19, water and foam concentrate fluid will be proportioned at proportional mixing valve 25. Referring now to FIG. 2, an enlarged side elevation view of a suitable proportional mixing valve is shown. Proportional mixing valve 25 comprises inputs for coupling to lines 23 and 24. The output of proportional mixing valve 25 is coupled to line 26 for transmitting the aqueous concentrate solution to foam generator 11. An appropriate form for proportional mixing valve 25 utilizes a concentrically disposed restriction 50 having an axial orifice 5] dis posed therein. The flow of water in line 23 and concentrate in line 24 are shown by the designated arrows. The location of the input from line 24 is downstream from restriction 50, the distance being ,a variable amount dependent upon the side of orifice 51. The combination of the size of orifice 51 and the distance between restriction 50 and input from line 24 will determine the pressure differential between restriction 50 and the input from line 24. The relationship between the size of orifice 51 and the placement of the input from line 24 can be determined by conventional fluid mechanics. In the configuration of proportional mixing valve 25 shown in FIG. 2, the pressure differential can be easily adapted to cause a given amount of foam concentrate fluid to be introduced at the input from line 24 to the stream of water passing through orifice 51. The preferred embodiment of the present invention requires a solution having more than 4% concentrate therefore it would be obvious to one having skill in the art to adapt the size of orifice 51 and the distance between restriction 50 and the input from line 24 to provide an appropriate pressure differential for properly proportioning the water and foam concentrate fluid. The devices described by the prior art typically utilize venturi inductors venting to the atmosphere in order to induce the proportioning of solution elements. The use .of a vented proportioning valve will substantially deteriorate the operation of a'system since the concentrate will be decomposed if in contact with oxygen and the water would evaporate from solution thereby changing the proportion of the elements. The use of a nonvented proportional mixing valve 25 such as that shown in FIG. 2 would substantially overcome the environmental problems introduced by the devices disclosed in the prior art.

The high expansion foam concentrate is typically by weight composed of 3.0 to 4.5 percent Neodol 24, 30 to 35 percent Neodol 23-3A, 26 to 30 percent butyl ether dietheolene glycol and the balance of 30.5 to 4] percent of water. The concentrate is further diluted by volume to a concentration exceeding 4 percent of the above foam concentrate and 96.0 percent water. Neodol 23-3A is defined in Shell Chemical Bulletin, I.C:674l and is an aqueous solution of ammonium salt of a sulfated primary alcohol ethoxylate containing on the average three ethylene oxide units. Neodol 23-3A can be characterized by a molecular weight of approximately 423, a concentrate of ethylene oxide by weight of 31.2'percent, a specific gravity :at 25 C of l.0l and a pH of 7.3. It is a light colored viscous liquid containing about 60 percent by weight surfactant and ethanol is included as a solubilizor. Neodol 25 is commercially available from the Shell Chemical Company. Neodol 25 designates an alcohol blend characterized by the symbol R-OI-I where R is a blend of linear primary alcohols with l2, 13, 14 and 15 carbon atoms. The physical characteristics of Neodol 25 are a molecular weight of approximately 207, a specific gravity at 35 C of 0.834, and a viscosity of 18.3 centipoise at F. A high expansion foam is distinguishable from low expansion foam concentrate by the expansion ratio which is defined by the volume of foam produced divided by the original volume of the concentrate. A high expansion concentrate has an expansion ratio of 300 to 1,500 while a low expansion concentrate has an expansion ratio of IO to 20. The preferable ratio for use in buildings is 600 to 700. The expansion ratio can be changed by changing the pressure imposed on the concentrate. Referring to FIG. 1, actuating pressure regulator valve 19 can be set for a pressure of 40 80 psi. When the pressure is applied to water and concentrate tanks 20 and 21 respectively, the concentrate will have an expansion ratio substantially in the range of 500 700. The amount of concentrate available for fire fighting can be increased by putting a plurality of concentrate tanks 21 in series. The means utilized to provide for a proportioned solution of water and foam concentrate such as that shown in FIG. 1 can be modified by other input systems for utilizing large bodies of water. In FIG. 1, water tank 20 was used to contain a fixed amount of water, the water being placed under pressure by the inert gaseous contents of container 17. An alternative embodiment of the present invention could utilize a non-pressurized tank with a conventional pump for increasing the pressure head of the water, the pressurized water being used as the input to proportional mixing valve and to supply the motivating pressure to the foam concentrate fluid in concentrate tank 21. In this embodiment, the size of orifice 51 and the distance between restriction 50 and the input from line 24 would have to be adapted for a greater proportion of concentrate since this embodiment would inherently cause some dilution of the foam concentrate. Another embodiment of the present invention could be tied dimaintained at a temperature which will permit free I flow, i.e., above 32 F. The foam concentrate should be maintained above F and therefore can be kept within the outer wall 14 of building 10 even though the water is exterior to the boundaries of building 10. This will decrease the heating costs as well as the total operating cost of a system.

An understanding of the generation of foam can be best gained by reference to FIG. 3. The concentrate solution is output from proportional mixing valve 25 and forced into line 26 and finally into manifold 60 with a resulting emission of concentrate at nozzle 61. Nozzle 61 can be attached to manifold 60 in any suitable manner but preferably by a threaded joint 62 as shown in FIG. 7. Referring to FIG. 7, nozzle 61 can have a spiral chamber 63 leading to an annular flanged output 64 which will produce an output emission forming a cone. Nozzles 61 are in spaced relation along manifold 60 as can be best seen in FIG. 3. The number of nozzles 61 coupled to manifold 25 can be any suitable number which will insure uniform distribution of solution upon multilayer screen 34, the preferred embodiment of the present invention utilizing a set of eleven nozzles 61 within each foam generator 11.

The concentrate cone 65 emitted by a nozzle 61 is such that all parts of the multilayer screen 34 will be reached by the concentrate cone 65. If eleven nozzles 61 are spaced along manifold 60 of a generator I], nitrogen pressure of 80 psi will produce approximately 3,000 cubic feet of foam per minute. If the distance between nozzles 61 is reduced or the nitrogen pressure increased, the foam generated per foot of generator can be varied.

The surface area created by the concentrate cone 65 (FIG. 8) is intersected by the foam generation screen 34. As shown in FIGS. 3"and 4, multilayer screen 34 is attached to top wall 30 and bottom wall 31 in a manner which will insure that multilayer screen 34 is substantially parallel to floor 16. Although the angle of top wall 30 with respect to floor 16 can be any suitable angle, it is preferably disposed at approximately 45 i 15 with respect to the surface of floor 16. Nozzles 61 are oriented with respect to the plane of top wall 30 and bottom wall 31 to insure that cone of foam concentrate 65 is uniformly distributed across multilayer screen 34. This is accomplished by making the axis of the cone 65 substantially parallel to top wall 30 and bottom wall 31.

Although the preferred embodiment of the present invention is adapted to be used within fixed structures and secured as shown in FIG. 1, it is within the scope of the present invention to provide for other means of supporting foam generator 11 and to secure the system within any enclosed structures having available water sources.

Referring now to FIG. 5 and FIG. 6, the structure of multilayer screen 34 can be best understood. In order to adapt multilayer screen 34 to produce the highest flow rate of foam, the surface area between the holes must be expanded to increase agitation. As set forth in applicants U.S. Letters Pat. No. 3,592,269, hammertone or crackle paint which increases the surface area is a solution to this problem, but one which will not permit generation of the flow rates available with the present invention. The present invention is substantially improved by utilizing multilayer screen 34 comprising first and second honeycombed layers 35 and 36 respectively. Honeycombed layer 35 substantially increases the surface area available for contact by the foam concentrate mixture thereby providing a greater surface area for increasing agitation. In addition, honeycombed layer 35 substantially increases the hole area to allow a greater flow of generated foam. Honeycombed layer 35 constitutes a plurality of adjacent hexagonal orifices bounded by the metallic honeycombed walls 71 forming honeycombed layer 35. Honeycombed layer 35 is selected to provide a proper balance between the surface area provided by metallic walls 71 and hexagonal orifices 70. Although it is within the scope of the invention to utilize any appropriate honeycombed layer 35, the preferred embodiment of the present invention utilizes honeycombed structure fabricated of raw or oxidized aluminum wherein the distance between opposed wall junctions of orifices 70 is approximately I4 inch. To provide adequate surface area, honeycombed layer 35 is approximately I; inch thick.

The outer layer. 36 of multilayer screen 34 is second honeycombed layer 36. Second honeycombed layer 36 is substantially similar to first honeycombed layer 35 in that it constitutes a plurality of adjacent hexagonal orifices 72 bounded by the metallic honeycombed walls 73. As can be seen in FIG. 5 and FIG. 6, the profile of second honeycombed layer 36 is substantially the same as that of first honeycombed layer 35 except that the distance between the opposed wall junctions of orifices 72 is approximately one-half that used for honeycombed layer 35, Le, as inch. The thickness of second honeycombed layer 36 is approximately V4 inch. The combination of honeycombed layers 35 and 36 allow generation of foam velocities substantially near the theoretical maximum. There is an optimum speed at which foam can be created, beyond which the strength of the film will not be sufficient to withstand the stresses imposed by the flow dynamics. The available free energy yields a theoretical maximum flow rate of approximately 650 feet per minute. lf this speed is surpassed, the foam bubbles will break upon contacting the air. The use of combined honeycombed screens 35 and 36 provide sufficient surface area to provide the needed agitation to allow generation of foam velocities of approximately 650 feet per minute. Reference to FIG. 9

illustrates the comparison between manifold pressure and foam velocity between the system defined by applicants co-pending application Ser. No. 160,810 filed July 8, 1971 indicated by curve (a) and the foam velocity produced by the present invention indicated by curve (b). It can be seen that the system defined by ap- .plicants copending application Ser. No. 160,810 ex- ,hibits a severe decrease in foam velocity after exceeding approximately 50 pounds per square inch of manifold pressure. The present invention illustrated by curve (b) shows the ability to approach the theoretical maximum of 650 feet per minute of foam at approximately 80 psi of manifold pressure. It can therefore be seen that the ability to produce high foam velocities by allowing use of higher manifold pressures is achieved by the present invention. The combination of honeycombed layers 35 and 36 substantially increases the available surface area and agitation of the foam concentrate producing a greater flow rate at designated pressure. In addition, the foam produced is substantially more homogenious permitting greaterpenetration of the area to be filled by the foam. Utilizing typical foam generator 1 1 having five square feet of generating area, morethan 3,000 cubic feet of foam per minute can be generated. i i

The operation of the present invention tire extinguishing system can be best seen by reference to FIG. 1,- FIG. 3 and FIG. 4 wherein foam. generators 11. are shown emittingfoam within the enclosed structure. As can be seen in FIG. 3, foam generator 11 is constructed to insure that the multilayer screen 34 is substantially horizontal and therefore parallel to the floor 16 of structure 10. Top wall 30 and bottom walls 31 and 33 are substantially parallel, top wall 30 and bottom wall 33 being joined by rear wall 32. Top wall 30 is joined to. bottom wall 31 at the lower edges thereof by multilayer screen 34; The lateral edges of walls 30 and 33 are joined by side walls not shown. The fabricated walls of foam generator 11 provide an orifice 80 between bottomwalls 31' and 33 through whichair can be drawn for mixing withthe eone 65 of foam concentrate to produce the generated foam.

Pressurized foam concentrate, proportioned and mixed at proportional mixing valve 25, is forced through manifold 60'and from nozzles6l producing cone 65 of mixed foam concentrate to contact multilayer screen 34, As stated, the flow axis of cone 65 of the foam concentrate mixture is substantially parallel to top wall 30 and bottom wall 31 to provide for substantially uniform distribution of the foam concentrate on honeycombed layer 35 of multilayer screen 34. The conic streem 65 of foam concentrate creates a partial vacuum drawing the heated air 181 into orifice defined by bottom walls 31 and 33 and the side walls joining walls 30 33. The mixture of air and the aqueous solution'of foam concentrate produces foam pile 82 through which heated air 81 is drawn. As stated, orifice 80 through which the partial vacuum draws heated air 81 is defined by an opening in bottom walls 31 and 33 laterally bounded by the side walls of foam generator 11. The drawing of heated air 81 through foam pile 82 substantially cools heated air 81. thereby accelerating the fire extinguishing process. Drawing heated air 81 through foam pile 82 is assured since top wall 30 and rear wall 32 substantiall shroud nozzles 61 thereby leaving the only point of entry at orifice 80. Heated air 81 will carry particles eminating from burning article 83 and this in turn will partially contaminate cone 65 of foam concentrate as can be seen in FIG. 8. The outer surface or skin of the cone 65 of concentrate will be impregnated with the contaminating particles but so long as the velocity of the concentrate is sufficient to prevent total impregnation of the cone 65, foam generation at multilayer screen 34 will be effective.

The present inventionfire extinguishing system produces a device which substantially solves problems existing in those devices disclosed by the prior art. The

present invention system is totally sealed utilizing an external source of water, but requires no external means for drawing air or other catalysts into foam generator l1to combine with the aqueous foam concentrate mixture for the generation of foam. Air is drawn through orifice 80 without the need of any fans or other air moving equipment. The combined mixture of aqueous foam concentrate and air strikes multilayer screen 34 thereby producing sufficient agitation to produce a stream of foam at velocities near 650 feet per minute. Multilayer screen 34 comprising honeycombed layers 35 and 36 allows use of relatively high manifold pressures to produce the high foam generating rates. The effectof these results permits the fabrication of the tire extinguishingsystem at substantially lower costs and without the problems inherent in those devices described by the prior art.

I claim:

1. An improved fire extinguishing system of the type employing high expansion foam, the improvement comprising:

a. a reservoir containing high expansion foa rn prob. fluid meansfor supplying a pressurized source of water coupled to said reservoir;

c. proportional mixing means coupled to said fluid means and said reservoir for combining the water and high expansion foam producing fluid in predetermined proportion; and

d. a foam generator comprising:

1. a plurality of nozzle members coupled to said proportional mixing means;

2. a screen horizontally disposed and oppositesaid nozzles, said foam generator having top, bottom, rear and side enclosures, said bottom enclosure extending from said screen to a distance substantially in the vicinity of said nozzles and said top enclosure extending from said screen substantially beyond said nozzles, said rear enclosure depending downwardly from said top enclosure defining an orifice whereby air is drawn into said foam generator through said orifice defined by said enclosures when fluid is caused to be discharged through said nozzles for projection upon said screen where said high expansion foam is generated.

2. The fire extinguishing systems defined in claim 1 wherein said screen is a multilayer screen.

3. The fire extinguishing system as defined in claim 2 wherein said multilayer screen comprises a first and second honeycombed layer each having a plurality of hexagonal cells disposed therethrough, said first honeycombed layer in intimate contact with said second honeycombed layer.

4. A fire extinguishing system as defined in claim 1 wherein said fluid means comprises:

a. a water reservoir;

b. a source of pressurized, inert gas; and

c. means coupling said source of pressurized, inert gas to said water reservoir and said foam concentrate reservoir.

5. A fire extinguishing system as defined in claim 4 wherein said inert gas is nitrogen.

6. A fire extinguishing system as defined in claim 1 wherein said fluid means comprises a source of pressurized water coupled to said proportional mixing means and said reservoir or foam concentrate.

7. A fire extinguishing system as defined in claim 1 wherein said pressurized source is pressurized in the range of 40 to 80 psi.

8. A fire extinguishing system of the type using high expansion foam comprising; I

a. self-contained source means for containing pressurized gas;

b. first reservoir means coupled to said self-contained source means for containing high expansion foam producing concentrate fluid;

c. a second reservoir for containing water coupled to said self-contained source means;

d. a proportional mixing valve having a pair of input lines and a single output line, said input lines being coupled to said first and second reservoirs respectively;

e. foam generating means fordrawing air into same and generating foam coupled to the output of said proportional mixing valve, said foam generating means comprising: l. a manifold having spaced openings therein coupled to said reservoir means; 2. a plurality of nozzles coupled to said spaced openings in said manifold, said nozzles adapted to output said foam producing concentrate mixture; 3. a multilayer screen horizontally disposed and being opposite said nozzles; and 4. an enclosure having top, bottom, rear and side walls, a portion of said top wall and said bottom wall being coupled to said multilayer screen, said enclosure defining an orifice through said bottom wall whereby the output of foam producing concentrate mixture from said nozzles causes ambient air to be drawn through said orifice.

9. A fire extinguishing system as defined in claim 8 wherein said multilayer screen comprises a first honeycombed layer having a plurality of hexagonal cells disposed therethrough and a second honeycombed layer in intimate contact with said first honeycombed layer, said second honeycombed layer having a plurality of hexagonal cells disposed therethrough being dimensionally smaller than those of said first honeycombed layer.

10. A fire extinguishing system as defined in claim 8 wherein said pressurized gas is an inert gas.

11. A fire extinguishing system as defined in claim 10 wherein said inert gas is nitrogen.

12. A fire extinguishing system as defined in claim 8 wherein said self-contained source means is pressurized in the range of 40 psi.

13. A self-contained fire extinguishing system of the type using high expansion foam comprising:

a. a source of pressurized,- inert gas;

b. at least one foam reservoir adapted to contain high expansion foam producing fluid, said reservoir coupled to said source of pressurized, inert gas;

c. a water reservoir coupled to said source of pressurized, inert gas;

d. a proportional mixing valve having a pair of input lines and a single output line, said input lines being coupled to said foam reservoir and said water reservoir respectively; and

. a foam generator having an enclosure of top, bottom, rear and side walls defining an orifice through said bottom wall, a multilayer screen including first and second honeycombed layers in intimate contact with each other, said multilayer screen being horizontally disposed and secured to protions of said top and bottom walls, a manifold having a plurality of spaced openings therein being disposed within said enclosure and coupled to the output of said proportional mixing valve, sand a plurality of nozzles each being coupled to one of said spaced openings and being opposite said multilayer screen and adapted to output said mixture of foam producing fluid uniformly upon said multilayer screen whereby the output of said foam producing fluid from said plurality of nozzles causes ambient air to" be drawn through said orifice.

14. A fire extinguishing system as defined in claim 13 wherein said first and second honeycombed layers each have a plurality of hexagonal cells disposed. therethrough, the hexagonal cells of said second honeycombed layer being smaller than the hexagonal cells of said first honeycombed layer.

15. A fire extinguishing system as defined in claim 13 wherein said inert gas is nitrogen.

16. A fire extinguishing system as defined in claim 13 wherein said inert gas is pressurized in the range of 40 80 psi. 

1. An improved fire extinguishing system of the type employing high expansion foam, the improvement comprising: a. a reservoir containing high expansion foam producing fluid; b. fluid means for supplying a pressurized source of water coupled to said reservoir; c. proportional mixing means coupled to said fluid means and said reservoir for combining the water and high expansion foam producing fluid in predetermined proportion; and d. a foam generator comprising:
 1. a plurality of nozzle members coupled to said proportional mixing means;
 2. a screen horizontally disposed and opposite said nozzles, said foam generator having top, bottom, rear and side enclosures, said bottom enclosure extending from said screen to a distance substantially in the vicinity of said nozzles and said top enclosure extending from said Screen substantially beyond said nozzles, said rear enclosure depending downwardly from said top enclosure defining an orifice whereby air is drawn into said foam generator through said orifice defined by said enclosures when fluid is caused to be discharged through said nozzles for projection upon said screen where said high expansion foam is generated.
 2. a screen horizontally disposed and opposite said nozzles, said foam generator having top, bottom, rear and side enclosures, said bottom enclosure extending from said screen to a distance substantially in the vicinity of said nozzles and said top enclosure extending from said Screen substantially beyond said nozzles, said rear enclosure depending downwardly from said top enclosure defining an orifice whereby air is drawn into said foam generator through said orifice defined by said enclosures when fluid is caused to be discharged through said nozzles for projection upon said screen where said high expansion foam is generated.
 2. The fire extinguishing systems defined in claim 1 wherein said screen is a multilayer screen.
 2. a plurality of nozzles coupled to said spaced openings in said manifold, said nozzles adapted to output said foam producing concentrate mixture;
 3. The fire extinguishing system as defined in claim 2 wherein said multilayer screen comprises a first and second honeycombed layer each having a plurality of hexagonal cells disposed therethrough, said first honeycombed layer in intimate contact with said second honeycombed layer.
 3. a multilayer screen horizontally disposed and being opposite said nozzles; and
 4. A fire extinguishing system as defined in claim 1 wherein said fluid means comprises: a. a water reservoir; b. a source of pressurized, inert gas; and c. means coupling said source of pressurized, inert gas to said water reservoir and said foam concentrate reservoir.
 4. an enclosure having top, bottom, rear and side walls, a portion of said top wall and said bottom wall being coupled to said multilayer screen, said enclosure defining an orifice through said bottom wall whereby the output of foam producing concentrate mixture from said nozzles causes ambient air to be drawn through said orifice.
 5. A fire extinguishing system as defined in claim 4 wherein said inert gas is nitrogen.
 6. A fire extinguishing system as defined in claim 1 wherein said fluid means comprises a source of pressurized water coupled to said proportional mixing means and said reservoir or foam concentrate.
 7. A fire extinguishing system as defined in claim 1 wherein said pressurized source is pressurized in the range of 40 to 80 psi.
 8. A fire extinguishing system of the type using high expansion foam comprising: a. self-contained source means for containing pressurized gas; b. first reservoir means coupled to said self-contained source means for containing high expansion foam producing concentrate fluid; c. a second reservoir for containing water coupled to said self-contained source means; d. a proportional mixing valve having a pair of input lines and a single output line, said input lines being coupled to said first and second reservoirs respectively; e. foam generating means for drawing air into same and generating foam coupled to the output of said proportional mixing valve, said foam generating means comprising:
 9. A fire extinguishing system as defined in claim 8 wherein said multilayer screen comprises a first honeycombed layer having a plurality of hexagonal cells disposed therethrough and a second honeycombed layer in intimate contact with said first honeycombed layer, said second honeycombed layer having a plurality of hexagonal cells disposed therethrough being dimensionally smaller than those of said first honeycombed layer.
 10. A fire extinguishing system as defined in claim 8 wherein said pressurized gas is an inert gas.
 11. A fire extinguishing system as defined in claim 10 wherein said inert gas is nitrogen.
 12. A fire extinguishing system as defined in claim 8 wherein said self-contained source means is pressurized in the range of 40 - 80 psi.
 13. A self-contained fire extinguishing system of the type using high expansion foam comprising: a. a source of pressurized, inert gas; b. at least one foam reservoir adapted to contain high expansion foam producing fluid, said reservoir coupled to said source of pressurized, inert gas; c. a water reservoir coupled to said source of pressurized, inert gas; d. a proportional mixing valve having a pair of input lines and a single output line, said input lines being coupled to said foam reservoir and said water reservoir respectively; and e. a foam generator having an enclosure of top, bottom, rear and side walls defining an orifice through said bottom wall, a multilayer screen including first and second honeycombed layers in intimate contact with each other, said multilayer screen being horizontally disposed and secured to protions of said top and bottom walls, a manifold having a plurality of spaced openings therein being disposed within said enclosure and coupled to the output of said proportional mixing valve, sand a plurality of nozzles each being coupled to one of said spaced openings and being opposite said multilayer screen and adapted to output said mixture of foam producing fluid uniformly upon said multilayer screen whereby the output of said foam producing fluid from said plurality of nozzles causes ambient air to be drawn through said orifice.
 14. A fire extinguishing system as defined in claim 13 wherein said first and second honeycombed layers each have a plurality of hexagonal cells disposed therethrough, the hexagonal cells of said second honeycombed layer being smaller than the hexagonal cells of said first honeycombed layer.
 15. A fire extinguishing system as defined in claim 13 wherein said inert gas is nitrogen.
 16. A fire extinguishing system as defined in claim 13 wherein said inert gas is pressurized in the range of 40 - 80 psi. 